#ifndef __EMAP_H__
#define __EMAP_H__

#include "EBase.hh"
#include "ESet.hh"
#include "ESharedPtr.hh"

namespace efc {

/**
 * An object that maps keys to values.  A map cannot contain duplicate keys;
 * each key can map to at most one value.
 *
 * <p>This interface takes the place of the <tt>Dictionary</tt> class, which
 * was a totally abstract class rather than an interface.
 *
 * <p>The <tt>Map</tt> interface provides three <i>collection views</i>, which
 * allow a map's contents to be viewed as a set of keys, collection of values,
 * or set of key-value mappings.  The <i>order</i> of a map is defined as
 * the order in which the iterators on the map's collection views return their
 * elements.  Some map implementations, like the <tt>TreeMap</tt> class, make
 * specific guarantees as to their order; others, like the <tt>HashMap</tt>
 * class, do not.
 *
 * <p>Note: great care must be exercised if mutable objects are used as map
 * keys.  The behavior of a map is not specified if the value of an object is
 * changed in a manner that affects <tt>equals</tt> comparisons while the
 * object is a key in the map.  A special case of this prohibition is that it
 * is not permissible for a map to contain itself as a key.  While it is
 * permissible for a map to contain itself as a value, extreme caution is
 * advised: the <tt>equals</tt> and <tt>hashCode</tt> methods are no longer
 * well defined on such a map.
 *
 * <p>All general-purpose map implementation classes should provide two
 * "standard" constructors: a void (no arguments) constructor which creates an
 * empty map, and a constructor with a single argument of type <tt>Map</tt>,
 * which creates a new map with the same key-value mappings as its argument.
 * In effect, the latter constructor allows the user to copy any map,
 * producing an equivalent map of the desired class.  There is no way to
 * enforce this recommendation (as interfaces cannot contain constructors) but
 * all of the general-purpose map implementations in the JDK comply.
 *
 * <p>The "destructive" methods contained in this interface, that is, the
 * methods that modify the map on which they operate, are specified to throw
 * <tt>UnsupportedOperationException</tt> if this map does not support the
 * operation.  If this is the case, these methods may, but are not required
 * to, throw an <tt>UnsupportedOperationException</tt> if the invocation would
 * have no effect on the map.  For example, invoking the {@link #putAll(Map)}
 * method on an unmodifiable map may, but is not required to, throw the
 * exception if the map whose mappings are to be "superimposed" is empty.
 *
 * <p>Some map implementations have restrictions on the keys and values they
 * may contain.  For example, some implementations prohibit null keys and
 * values, and some have restrictions on the types of their keys.  Attempting
 * to insert an ineligible key or value throws an unchecked exception,
 * typically <tt>NullPointerException</tt> or <tt>ClassCastException</tt>.
 * Attempting to query the presence of an ineligible key or value may throw an
 * exception, or it may simply return false; some implementations will exhibit
 * the former behavior and some will exhibit the latter.  More generally,
 * attempting an operation on an ineligible key or value whose completion
 * would not result in the insertion of an ineligible element into the map may
 * throw an exception or it may succeed, at the option of the implementation.
 * Such exceptions are marked as "optional" in the specification for this
 * interface.
 *
 * <p>This interface is a member of the
 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
 * Java Collections Framework</a>.
 *
 * <p>Many methods in Collections Framework interfaces are defined
 * in terms of the {@link Object#equals(Object) equals} method.  For
 * example, the specification for the {@link #containsKey(Object)
 * containsKey(Object key)} method says: "returns <tt>true</tt> if and
 * only if this map contains a mapping for a key <tt>k</tt> such that
 * <tt>(key==null ? k==null : key.equals(k))</tt>." This specification should
 * <i>not</i> be construed to imply that invoking <tt>Map.containsKey</tt>
 * with a non-null argument <tt>key</tt> will cause <tt>key.equals(k)</tt> to
 * be invoked for any key <tt>k</tt>.  Implementations are free to
 * implement optimizations whereby the <tt>equals</tt> invocation is avoided,
 * for example, by first comparing the hash codes of the two keys.  (The
 * {@link Object#hashCode()} specification guarantees that two objects with
 * unequal hash codes cannot be equal.)  More generally, implementations of
 * the various Collections Framework interfaces are free to take advantage of
 * the specified behavior of underlying {@link Object} methods wherever the
 * implementor deems it appropriate.
 *
 * @param <K> the type of keys maintained by this map
 * @param <V> the type of mapped values
 *
 * @version 1.56, 04/21/06
 * @see HashMap
 * @see TreeMap
 * @see Hashtable
 * @see SortedMap
 * @see Collection
 * @see Set
 * @since 1.2
 */

/**
 * A map entry (key-value pair).  The <tt>Map.entrySet</tt> method returns
 * a collection-view of the map, whose elements are of this class.  The
 * <i>only</i> way to obtain a reference to a map entry is from the
 * iterator of this collection-view.  These <tt>Map.Entry</tt> objects are
 * valid <i>only</i> for the duration of the iteration; more formally,
 * the behavior of a map entry is undefined if the backing map has been
 * modified after the entry was returned by the iterator, except through
 * the <tt>setValue</tt> operation on the map entry.
 *
 * @see Map#entrySet()
 * @since 1.2
 */

template<typename K, typename V>
interface EMapEntry : virtual public EObject {
	virtual ~EMapEntry() {
	}

	/**
	 * Returns the key corresponding to this entry.
	 *
	 * @return the key corresponding to this entry
	 * @throws IllegalStateException implementations may, but are not
	 *         required to, throw this exception if the entry has been
	 *         removed from the backing map.
	 */
	virtual K getKey() = 0;

	/**
	 * Returns the value corresponding to this entry.  If the mapping
	 * has been removed from the backing map (by the iterator's
	 * <tt>remove</tt> operation), the results of this call are undefined.
	 *
	 * @return the value corresponding to this entry
	 * @throws IllegalStateException implementations may, but are not
	 *         required to, throw this exception if the entry has been
	 *         removed from the backing map.
	 */
	virtual V getValue() = 0;

	/**
	 * Replaces the value corresponding to this entry with the specified
	 * value (optional operation).  (Writes through to the map.)  The
	 * behavior of this call is undefined if the mapping has already been
	 * removed from the map (by the iterator's <tt>remove</tt> operation).
	 *
	 * @param value new value to be stored in this entry
	 * @return old value corresponding to the entry
	 * @throws UnsupportedOperationException if the <tt>put</tt> operation
	 *         is not supported by the backing map
	 * @throws ClassCastException if the class of the specified value
	 *         prevents it from being stored in the backing map
	 * @throws NullPointerException if the backing map does not permit
	 *         null values, and the specified value is null
	 * @throws IllegalArgumentException if some property of this value
	 *         prevents it from being stored in the backing map
	 * @throws IllegalStateException implementations may, but are not
	 *         required to, throw this exception if the entry has been
	 *         removed from the backing map.
	 */
	virtual V setValue(V value) = 0;

	/**
	 * Compares the specified object with this entry for equality.
	 * Returns <tt>true</tt> if the given object is also a map entry and
	 * the two entries represent the same mapping.  More formally, two
	 * entries <tt>e1</tt> and <tt>e2</tt> represent the same mapping
	 * if<pre>
	 *     (e1.getKey()==null ?
	 *      e2.getKey()==null : e1.getKey().equals(e2.getKey()))  &amp;&amp;
	 *     (e1.getValue()==null ?
	 *      e2.getValue()==null : e1.getValue().equals(e2.getValue()))
	 * </pre>
	 * This ensures that the <tt>equals</tt> method works properly across
	 * different implementations of the <tt>Map.Entry</tt> interface.
	 *
	 * @param o object to be compared for equality with this map entry
	 * @return <tt>true</tt> if the specified object is equal to this map
	 *         entry
	 */
	virtual boolean equals(EMapEntry<K,V> *o) = 0;

	/**
	 * Returns the hash code value for this map entry.  The hash code
	 * of a map entry <tt>e</tt> is defined to be: <pre>
	 *     (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
	 *     (e.getValue()==null ? 0 : e.getValue().hashCode())
	 * </pre>
	 * This ensures that <tt>e1.equals(e2)</tt> implies that
	 * <tt>e1.hashCode()==e2.hashCode()</tt> for any two Entries
	 * <tt>e1</tt> and <tt>e2</tt>, as required by the general
	 * contract of <tt>Object.hashCode</tt>.
	 *
	 * @return the hash code value for this map entry
	 * @see Object#hashCode()
	 * @see Object#equals(Object)
	 * @see #equals(Object)
	 */
	virtual int hashCode() = 0;
};

template<typename K, typename V>
class EImmutableEntry: public EMapEntry<K, V> {
private:
	K key;
	V value;

	static boolean eq(EObject* o1, EObject* o2) {
		return o1 == null ? o2 == null : o1->equals(o2);
	}
public:
	virtual ~EImmutableEntry(){}

	/**
	 * Creates an entry representing a mapping from the specified
	 * key to the specified value.
	 *
	 * @param key the key represented by this entry
	 * @param value the value represented by this entry
	 */
	EImmutableEntry(K key, V value) {
		this->key = key;
		this->value = value;
	}

	/**
	 * Returns the key corresponding to this entry.
	 *
	 * @return the key corresponding to this entry
	 */
	K getKey() {
		return key;
	}

	/**
	 * Returns the value corresponding to this entry.
	 *
	 * @return the value corresponding to this entry
	 */
	V getValue() {
		return value;
	}

	/**
	 * Set our entry's value and write through to the map. The
	 * value to return is somewhat arbitrary here. Since a
	 * WriteThroughEntry does not necessarily track asynchronous
	 * changes, the most recent "previous" value could be
	 * different from what we return (or could even have been
	 * removed in which case the put will re-establish). We do not
	 * and cannot guarantee more.
	 */
	V setValue(V value) {
		throw EUNSUPPORTEDOPERATIONEXCEPTION;
	}

	boolean equals(EMapEntry<K, V>* o) {
		return eq(key.get(), o->getKey().get()) && eq(value.get(), o->getValue().get());
	}

	virtual int hashCode() {
		return (key   == null ? 0 : key->hashCode()) ^
				(value == null ? 0 : value->hashCode());
	}
};

//=============================================================================

template<typename K, typename V>
interface EMap : virtual public EObject {
	typedef typename ETraits<K>::indexType idxK;
	typedef typename ETraits<V>::indexType idxV;

	virtual ~EMap() {
	}

	// Query Operations

	/**
	 * Returns the number of key-value mappings in this map.  If the
	 * map contains more than <tt>Integer.MAX_VALUE</tt> elements, returns
	 * <tt>Integer.MAX_VALUE</tt>.
	 *
	 * @return the number of key-value mappings in this map
	 */
	virtual int size() = 0;

	/**
	 * Returns <tt>true</tt> if this map contains no key-value mappings.
	 *
	 * @return <tt>true</tt> if this map contains no key-value mappings
	 */
	virtual boolean isEmpty() = 0;

	/**
	 * Returns <tt>true</tt> if this map contains a mapping for the specified
	 * key.  More formally, returns <tt>true</tt> if and only if
	 * this map contains a mapping for a key <tt>k</tt> such that
	 * <tt>(key==null ? k==null : key.equals(k))</tt>.  (There can be
	 * at most one such mapping.)
	 *
	 * @param key key whose presence in this map is to be tested
	 * @return <tt>true</tt> if this map contains a mapping for the specified
	 *         key
	 * @throws ClassCastException if the key is of an inappropriate type for
	 *         this map (optional)
	 * @throws NullPointerException if the specified key is null and this map
	 *         does not permit null keys (optional)
	 */
	virtual boolean containsKey(idxK key) = 0;

	/**
	 * Returns <tt>true</tt> if this map maps one or more keys to the
	 * specified value.  More formally, returns <tt>true</tt> if and only if
	 * this map contains at least one mapping to a value <tt>v</tt> such that
	 * <tt>(value==null ? v==null : value.equals(v))</tt>.  This operation
	 * will probably require time linear in the map size for most
	 * implementations of the <tt>Map</tt> interface.
	 *
	 * @param value value whose presence in this map is to be tested
	 * @return <tt>true</tt> if this map maps one or more keys to the
	 *         specified value
	 * @throws ClassCastException if the value is of an inappropriate type for
	 *         this map (optional)
	 * @throws NullPointerException if the specified value is null and this
	 *         map does not permit null values (optional)
	 */
	virtual boolean containsValue(idxV value) = 0;

	/**
	 * Returns the value to which the specified key is mapped,
	 * or {@code null} if this map contains no mapping for the key.
	 *
	 * <p>More formally, if this map contains a mapping from a key
	 * {@code k} to a value {@code v} such that {@code (key==null ? k==null :
	 * key.equals(k))}, then this method returns {@code v}; otherwise
	 * it returns {@code null}.  (There can be at most one such mapping.)
	 *
	 * <p>If this map permits null values, then a return value of
	 * {@code null} does not <i>necessarily</i> indicate that the map
	 * contains no mapping for the key; it's also possible that the map
	 * explicitly maps the key to {@code null}.  The {@link #containsKey
	 * containsKey} operation may be used to distinguish these two cases.
	 *
	 * @param key the key whose associated value is to be returned
	 * @return the value to which the specified key is mapped, or
	 *         {@code null} if this map contains no mapping for the key
	 * @throws ClassCastException if the key is of an inappropriate type for
	 *         this map (optional)
	 * @throws NullPointerException if the specified key is null and this map
	 *         does not permit null keys (optional)
	 */
	virtual V get(idxK key) = 0;

	// Modification Operations

	/**
	 * Associates the specified value with the specified key in this map
	 * (optional operation).  If the map previously contained a mapping for
	 * the key, the old value is replaced by the specified value.  (A map
	 * <tt>m</tt> is said to contain a mapping for a key <tt>k</tt> if and only
	 * if {@link #containsKey(Object) m.containsKey(k)} would return
	 * <tt>true</tt>.)
	 *
	 * @param key key with which the specified value is to be associated
	 * @param value value to be associated with the specified key
	 * @return the previous value associated with <tt>key</tt>, or
	 *         <tt>null</tt> if there was no mapping for <tt>key</tt>.
	 *         (A <tt>null</tt> return can also indicate that the map
	 *         previously associated <tt>null</tt> with <tt>key</tt>,
	 *         if the implementation supports <tt>null</tt> values.)
	 * @throws UnsupportedOperationException if the <tt>put</tt> operation
	 *         is not supported by this map
	 * @throws ClassCastException if the class of the specified key or value
	 *         prevents it from being stored in this map
	 * @throws NullPointerException if the specified key or value is null
	 *         and this map does not permit null keys or values
	 * @throws IllegalArgumentException if some property of the specified key
	 *         or value prevents it from being stored in this map
	 */
	virtual V put(K key, V value, boolean *absent=null) = 0;

	/**
	 * Removes the mapping for a key from this map if it is present
	 * (optional operation).   More formally, if this map contains a mapping
	 * from key <tt>k</tt> to value <tt>v</tt> such that
	 * <code>(key==null ?  k==null : key.equals(k))</code>, that mapping
	 * is removed.  (The map can contain at most one such mapping.)
	 *
	 * <p>Returns the value to which this map previously associated the key,
	 * or <tt>null</tt> if the map contained no mapping for the key.
	 *
	 * <p>If this map permits null values, then a return value of
	 * <tt>null</tt> does not <i>necessarily</i> indicate that the map
	 * contained no mapping for the key; it's also possible that the map
	 * explicitly mapped the key to <tt>null</tt>.
	 *
	 * <p>The map will not contain a mapping for the specified key once the
	 * call returns.
	 *
	 * @param key key whose mapping is to be removed from the map
	 * @return the previous value associated with <tt>key</tt>, or
	 *         <tt>null</tt> if there was no mapping for <tt>key</tt>.
	 * @throws UnsupportedOperationException if the <tt>remove</tt> operation
	 *         is not supported by this map
	 * @throws ClassCastException if the key is of an inappropriate type for
	 *         this map (optional)
	 * @throws NullPointerException if the specified key is null and this
	 *         map does not permit null keys (optional)
	 */
	virtual V remove(idxK key) = 0;

	/**
	 * Removes all of the mappings from this map (optional operation).
	 * The map will be empty after this call returns.
	 *
	 * @throws UnsupportedOperationException if the <tt>clear</tt> operation
	 *         is not supported by this map
	 */
	virtual void clear() = 0;

	// Views

	/**
	 * Returns a {@link Set} view of the keys contained in this map.
	 * The set is backed by the map, so changes to the map are
	 * reflected in the set, and vice-versa.  If the map is modified
	 * while an iteration over the set is in progress (except through
	 * the iterator's own <tt>remove</tt> operation), the results of
	 * the iteration are undefined.  The set supports element removal,
	 * which removes the corresponding mapping from the map, via the
	 * <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
	 * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt>
	 * operations.  It does not support the <tt>add</tt> or <tt>addAll</tt>
	 * operations.
	 *
	 * @return a set view of the keys contained in this map
	 */
	virtual ESet<K>* keySet() = 0;

	/**
	 * Returns a {@link Collection} view of the values contained in this map.
	 * The collection is backed by the map, so changes to the map are
	 * reflected in the collection, and vice-versa.  If the map is
	 * modified while an iteration over the collection is in progress
	 * (except through the iterator's own <tt>remove</tt> operation),
	 * the results of the iteration are undefined.  The collection
	 * supports element removal, which removes the corresponding
	 * mapping from the map, via the <tt>Iterator.remove</tt>,
	 * <tt>Collection.remove</tt>, <tt>removeAll</tt>,
	 * <tt>retainAll</tt> and <tt>clear</tt> operations.  It does not
	 * support the <tt>add</tt> or <tt>addAll</tt> operations.
	 *
	 * @return a collection view of the values contained in this map
	 */
	virtual ECollection<V>* values() = 0;

	/**
	 * Returns a {@link Set} view of the mappings contained in this map.
	 * The set is backed by the map, so changes to the map are
	 * reflected in the set, and vice-versa.  If the map is modified
	 * while an iteration over the set is in progress (except through
	 * the iterator's own <tt>remove</tt> operation, or through the
	 * <tt>setValue</tt> operation on a map entry returned by the
	 * iterator) the results of the iteration are undefined.  The set
	 * supports element removal, which removes the corresponding
	 * mapping from the map, via the <tt>Iterator.remove</tt>,
	 * <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt> and
	 * <tt>clear</tt> operations.  It does not support the
	 * <tt>add</tt> or <tt>addAll</tt> operations.
	 *
	 * @return a set view of the mappings contained in this map
	 */
	virtual ESet<EMapEntry<K, V>*>* entrySet() = 0;
};

} /* namespace efc */
#endif //!__EMAP_H__
